Hurricane Harvey increased the risk of serious medical complications in both pregnant women and their newborn babies, according to a Houston study that adds to the list of physical and mental health problems caused by the storm.

Baylor College of Medicine researchers found complications spiked by 27 percent in mothers and 50 percent in infants in the 40 weeks following Harvey’s landfall, despite the group having fewer “at-risk” characteristics. The study, to be published in the November issue of Obstetrics and Gynecology, went online this week.

“Reproduction is a constant in history so you might think there’s a certain resiliency built-in despite stressful events,” said Dr. Kjersti Aagaard, a Baylor obstetrician-gynecologist and the senior author of the study. “But this study shows the dramatic effect a natural disaster can have.”

The study, which focused on roughly 3,800 deliveries, represents the largest and most robust look thus far into the August 2017 storm’s effect on pregnancy. It did not examine the reasons for the increased complications. Aagaard’s team is now working to determine such causes in a follow-up study.

Previous studies have suggested pregnant patients are vulnerable because disasters typically disrupt medical services and increase stress levels, which are linked to poor outcomes. But because evolution has shown that “maternal handling of stress is generally strong,” Aagaard says stress “might not be the real culprit here.” She speculates that environmental chemical exposure following Harvey might have contributed.

Researchers have previously shown Harvey led to an increase in skin infections, including flesh-eating bacterial disease; respiratory distress, such as that caused by allergies and asthma; and mental health difficulties, such as lingering intrusive or unintended worries about the storm.

The new study is part of ongoing research into pregnancy-related complications in Texas generally, which until recently was little noticed but now is considered a crisis. The research has mostly focused on maternal deaths and disease, significantly worse than other Western nations, but has also uncovered pockets of infant mortality around the state.

Harvey did not increase deaths in the women or their babies, according to the study, but did increase health problems regardless of the stage the pregnancy was in when Harvey hit. Problems included a need for blood transfusions, bacterial infections and high-blood pressure in women and respiratory distress and sepsis in infants.

Pregnancies in women of a lower socioeconomic status were found to have the greatest increase in complications.

One expert who has done work in the field said the new research shows pregnant women and newborns deserve special attention in the wake of such disasters.

“What the study does suggest is that both first responders and medical personnel should be aware that pregnant women exposed to these kinds of conditions are at increased risk and that they and their newborns may require a higher level of care than would otherwise be the case,” said Janet Currie, co-director of the Center for Health and Wellbeing at Princeton University.

Currie praised the study’s “detailed data” on the types of conditions, such as high blood pressure, that were more prevalent after the hurricane. She said “knowing more about the types of risk is helpful for knowing how to help these women and their babies.”

Aagaard’s team focused on deliveries at Ben Taub and the Texas Children’s Pavilion for Women between Aug. 25 2017, the day Harvey made landfall in Houston, and 280 days thereafter. The women, who on average were less likely to be obese and more likely to be older, white and married and have private insurance, were compared with women who gave birth at those hospitals during the previous six years.

Researchers drew on a database containing information from medical records, specimens collected at the time of the patient’s arrival and direct queries. They added a series of questions in the patient’s native language about the perceived effects of the storm on themselves and their possessions.

Before Harvey, 2,900 of 25,337 mothers, or 11.5 percent, suffered a significant complication, compared with 564 of 3,842 mothers, or 14.7 percent, after the storm. Among newborns, 1,965 of 25,337, or 7.8 percent, had significant medical conditions before the storm, compared with 456 of 3,842, or 11.9 percent, after the storm.

There was no change in the premature birth rate. The cesarean delivery rate increased by 5 percent, which was not appreciably different than the 6 to 10 percent increase in affected areas during and after Hurricane Katrina.

Currie suggested the loss of homes, vehicles and jobs as a result of Harvey made the socioeconomic differences predictable.

“People with greater resources could be more confident of being able to rebuild, as well as being able to afford better conditions in the short run,” said Currie, whose research includes an investigation into birth outcomes in Texas in women in the projected path of a hurricane between 1996 to 2008 who ended up not getting hit. “Poorer people are likely to have had a much more stressful experience struggling to cope with the aftermath and more uncertainty about the future.”

But Aagaard emphasized the greater effect on those of lower socioeconomic status occurred independent of whether the women identified their household as affected by Harvey or whether they perceived stress in response to the hurricane.

Aagaard’s follow-up research into the cause of the increase will target polycyclic aromatic hydrocarbons, or PAHs, a type of pollutant previously found to be higher in premature babies delivered closed to Superfund sites in Harris County. A 2018 Texas A&M study found Harvey redistributed PAHs in one Superfund neighborhood.

Aagaard said the pursuit of the increase’s underlying biological cause is a major priority but also noted the study’s practical value.

“It is our sincere hope that this study may provide other colleagues and health care professionals with the initial data that are necessary for efforts aimed at prioritizing resources to susceptible individuals during an emergency,” Aagaard concluded in the journal article.

Todd Ackerman is a veteran reporter who has covered medicine for the Houston Chronicle since 2001. A graduate of the University of California at Los Angeles, he previously worked for the Raleigh News & Observer, the National Catholic Register, the Los Angeles Downtown News and the San Clemente Sun-Post.